Block signal system for railroads



March 27, 1928. 1,664,108

w. s. HENRY BLOCK SIGNAL SYSTEM FOR RAILROADS Filed July 26. 1926 CD Lu "z wff 4 .1 ATTORNEY Patented Mar. 27, 1928.

UNITED STATES 1,664,108 PATENT OFFICE.

WILLIAM S. HENRY, OF ROCHESTER, NEW, YORK, ASSIGNOR TOv GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK.

:sLoo sreNAL SYSTEM non RAILROADS.

Application filed July 26,

This invention relates to automatic block signal systems for railroads, and more particularly to a system employing semaphore signals and polarized track circuits.

The principal object of the present inven-.

tion is to provide a circuit arrangement, employing simple and well known devices, to check the operation-of each signal and cause the signal in the rear to indicate stop in the event'that the signal ahead fails for any reason to assume the stop position. More specifically, it is proposed to include a front contact of the track relay of each block in the track circuit feed for the block next in the rear, and shunt this front contact if the semaphore signal governed by said track relay actually assumes its stop position, so that current is cut off from the track circuit in the block in the rear and the signal thereof put to stop unless the signal ahead actually moves to the stop position and operates the pole changer.

Various other characteristic features and advantages of theinvention will be in part appareutto those skilled 'in the art, and in part pointed out as the descriptionprogresses. I

The accompanying drawing shows in a simplifiedand diagrammatic manner, in accordance with established conventions, one embodiment of the invention.

The invention is particularly applicable to a well known type of block signal system employing semaphore signals and polarized track circuits. The track rails 1' are divided by insulated joints 2 into blocks, one block D with the adjacent ends of two other blocks C and Ejbeing shown. Disregarding cut sections, intermediate sidings, and the like, the circuit arrangement and equipment for each block may be assumed to be the same; and for convenience corresponding parts for I the difierent blocks are given the same ref erence characters with distinctive exponents.

1926; Serial No. 124,965.

Each block has a polarized track relay T connected. across the track rails at the entrance end of that block in conformity with recognlzed practice. In the particular form of the invention shown, thisrelay is assumed to be; a direct current neutral polar relay; but it should be understood that the invention is'applicableas well to systems employ- 1ng alternating current polarized track circuits. At the entrance to each block is a semaphore signal S, which is controlled in the usual way through a front contact of a neutral armature 3 and normal and re verse contacts of the polar armature 4,

Each signal operates a pole changer PC, shown conventionally, this pole changer being mechanically shifted at an intermediate point in the movement of the signal between its caution or 45 degree positio'n and its stop or zero. degree position, this point ordinarily being about 43 degrees above the horizontal. Also associated with'each signal is a circuit breaker or controller, of the usual construction, which is mechanically operated by the signal. This circuit breaker GB is shown in accordance with established convention, and is adjusted to close its contacts in'the zero degree or stop position of the signal.

The track battery 5 is connected to the pole changer PC of the signal at theentrance to the next block in advance. One terminal of the pole changer PC is connected by a wire 6 to one of the track rails at'the exit end of the block next in the rear. The other terminal of the pole, changer- PC is oonnected by wires 7 and 8, front contact 9 of the' track relay and wire 10 to the other trackrail of said block. Front contact 9 of the track relay is shunted by a'wire ll'and the contacts of the circuit breaker CB.

Normally, when notrains are present,'the parts and circuits assume the position shown in the drawing. Each signal S is in the clear position, its pole changer PC is .in the normal position supplying current of normal polarity to the track circuit in the rear through the front contact 9 of the track relay T. When a train enters a block, as the block D, the track relay T is shunted and opens its front contacts 3 and 9. The opening of the front contact 3 cuts off current from the signal S, which moves toward its low its 45 degree or caution position,the pole changer PC is shifted; and when, the signal reaches its horizontal position, the contacts of the circuit breaker CB close, thereby establishing a supply of track circuit current i of reverse polarity to'the block G in the rear through the shunt around the track relay contact 9 through the circuit breaker con tacts and wire 11. If the signal is stuck clear, or for any other reasonfails to assume 1" the stop position, the opening of the front contact 9 of the track rela T maintains current cut olf from the tract circuit of the block in the rear, holding the signalinthe rear at stop. YlVhen the train in question advances out of the block .D, the direction of traflic being from left. to right as, indicatedby the arrow, the track relay T picks up and clears thesignal S to the caution position, assuming of course that; the signal S for. the block E operates properly. This movement of the signal: reverses the pole changer PC, and the track circuit current of, the normalpolarity, supplied to the block C, allowing the signalatthelentrance to said, 5 block C to clear to the proceedposition.

It .will be noted that when a train enters a block, as the block 1), current to thetrack circuit of the block C next in the rear is temporarily cut off upon opening of the track,

relay contact 9 until the contacts of, the cincuit. breaker (1B close. This time is relatively short, and is that. taken for a semaphore signalto move from its proceed positionto the stop position. Ordinarily, the rear end of the train entering the block D will be inthe block G, holding the signal for block 0 at stop, due to the shunting of the,- track. relay for the block C, so that such; temporary interruption of track circuit: feed,

is notmaterial. In any event,such interruption merely delays the time of clearing. the

signal in the rear.

The particular embodiment of the inven:

tion shownand described is merely typical. and. representative; and I. desire to have it,

understood that various modifications and adaptations may be made in the particularconstruction and arrangement of j circuits shown and described without departing fronr the invention. -What I claim is I p '1. In a block signaling system fonrailroadshaving tracks divided into blocks, semaphore at the entrance to each. block, a polarized track relay atthe entrance end of. each. block governing said signal, a pole relay for supplying track circuit current to the block next in the rear, and. circuit controlling means operated by the signal for. shunting said front contact of the come spending track. relay saidv signalis in its stop position.

2. A block signaling system for railroads having polarized track circuits comprising, in combination with a polarized track relay foreacl'rblock, a semaphore signal at the entrance to each block a pole changer operated by each signal, of a source of current and circuit connections governed by said pole changer for'reversing the polarity of track circuit current. supplied: to the block next in therear of the corresponding signal,, said: electrical connections including in, multiple a front contact; ofthetrackrelay oftheblock. corresponding to. the signal and; said. circuit controller of, that. signal, whereby de-enen gization of atrackrelay of. a given block will; cut. off. current of; the track, circuit tothe block. next in the rear unless-the signali for said given blockassumes its stop pos t on,

' In a; block signaling system of. the type described including; polarized track circuits sition, electrical. connections between said;

current source-and. the track rails for supplying track circuit current. to each block, including a.

said electrical connections fronta contact of. the track. relay of.- the block; next inadvance, whereby de-ener-v gization of. the; track relay. of a given:

block cuts off the track. circuit. current for the block. in the. rear, and means dependent:

upon: the movementtof a given .signalito; its

stop position. for; supplying said trackcircuit current to the block intthe rear independently of saidtraok relay.

{l lmablock signal systemof the character described, a block provided with a track relay, a semaphore signal at theentranceato said block,.a-pole changer operatediby said signal, and closed. in its-stop position, and electrical: connections, between; said pole.

changer, and .atrackiin the rear of said block including a front contact of said track relay.

5. In a block. signal systemof; the character. described, including; polarized track: circuits, the combination with: a track circuit and its track relay, a semaphore signal. goverened, by: said track relay, a ,circuit controller operated by. ther signal; and having;

contacts closed onlyif saidsignalrisinthe stop position, and eleetr-icaliconnections for- 6. In. a, block; signal system, the combi-j nation with a railway. track. divided intoblocks, a; track; circuit for. eaeh block including a, tra ck. relay, means a at the entrance 7 of one block, responsive-to. the. condition of occupancy of that block and the next block is occupied and connected in series with the in advance having contacts associated theretrack circuit of the block in the rear, and a with for applying track circuit current to contact closed when the track relay of'said 10 the next block in the rear of said one block one block is energized for shunting said 5 of a polarity depending upon the condition control contact.

of said means, a control contact controlled In testimony whereof I aflix mysignature. by said means closed when said one block WILLIAM S. HENRY. I 

